An old bridge with weight restrictions that prevented a fire truck from reaching a call could cost $2.76 million to replace.
The deteriorating condition of the bridge, in a remote area on the north-west side of Lake Tekapo, and a number of safety issues have been highlighted in a report presented to the Mackenzie District Council on Tuesday.
The report examines the possible replacement of the 124 m single-lane, multi-span wooden structure, with a total estimated cost of $2.76 million.
The report, compiled by David Adamson, the council’s general manager of operations, planning and regulatory services, says Godley Peaks Station, Timaru Boys’ High School (TBHS), Department of Conservation (DOC), Land Information New Zealand (LINZ) and the public are all users of the bridge.
READ MORE:
* Mackenzie council severance pay to staff exceeds $300,000 in past five years
* Flooding damaged roads and bridges to cost councils more than $6 million
* New conservation land will be created in Mackenzie Country
Adamson said weight restrictions were first placed on the bridge in 2005, and height restriction barriers were erected more recently.
“The bridge is now heavily restricted, with the last inspection in December 2020 indicating that the axles are restricted to a weight of 3,000kg and the gross weight to 5,000kg with a speed restriction of 10km/h.
“This level of restriction essentially reduces the bridge to only providing light vehicle access.”
Adamson said the only way heavy vehicles could cross was through a ford about 400m downstream.
The council had a 30-year resource authorization that allowed it to carry out works on the river bed to maintain the ford. This work was largely carried out by Verity Farms, the station’s current lessee/owner.
“The ford cannot be used in bad weather conditions, after which it must be cleared by Verity Farms. The weight restriction also prevents emergency vehicles from accessing it, leading to safety issues.”
An event on January 28, 2021 highlighted these concerns. Adamson said a fire broke out 400m north of the bridge and firefighters were hesitant to cross the ford. The decision was made to empty the tank to cross the bridge, which took 35-40 minutes.
“A tanker collision with the bridge entrance caused additional delays before the tank was filled and the fire reported. At this time the fire was under control by Godley Peaks personnel.
“Verity Farms had expressed significant safety concerns due to a lack of emergency services coverage.”
Adamson said sometimes the only way to get heavy vehicles over the ford was to tow them.
“There are risks associated with the ford as the loads include hazardous chemicals, potential pollutants if released and some recreational users also take the opportunity to bring the fan down which threatens birds and other natural values.”
Adamson said the bridge has deteriorated over time and was nearing the end of its remaining useful life.
“The use of the ford by Verity Farms has slowed the deterioration of the bridge, extending its useful life.”
Adamson said a replacement bridge was needed to ensure continued access, and the council needed to consider replacing it with a HGV accessible bridge.
“There are approximately 100 HGV movements (50 return trips) in and out of the station annually across the ford, which equates to two movements per week.
John Bisset/Things
The ill bridge over the Cass River to Godley Peaks Station. (File photo)
“New trucks with technological and electronic advances do not cope well with deep river crossings.
“Hot oils in gearboxes and differentials can contract when quickly cooled in ice water, thus drawing water past the seals. This contaminates oils and other lubricants leading to premature failures and other problems.”
Adamson also said trucks are getting bigger and axle loads were typically balanced, meaning they didn’t have good riverbed traction.
“Typically, the ford must be held before vehicles cross to ensure a sufficiently stable footing over the main flow, as the bed is constantly moving as it is an alluvial base.”
Adamson said the council had no legal obligation to replace the bridge, but the bridge was an integral part of its network and the decision was considered significant.
“The current state, the height and weight restrictions have created many problems for Verity Farms.
“They cannot move livestock, fertilizer, wool, diesel, logs, silage and farm equipment across the bridge, all of which make up their business operations. As a result, Verity Farms must use the ford to allow heavy vehicles to pass. access the property and manage a working farm.”
JOHN KIRK-ANDERSON/THINGS
New fire trucks have arrived at Nelson, Queenstown, Dunedin and Invercargill airports
Adamson said Verity Farms was responsible for maintaining the ford, which was estimated to cost about $50,000 a year.
Adamson said if the bridge replacement was placed within the council’s roads program it could attract a 51% grant and suggested it be included in the next Long Term Plan for public consultation.
High level discussions have taken place regarding the possibility of Verity Farms contributing financially to the replacement of the bridge to ensure it is suitable for their needs.
“Although they have expressed a great willingness to contribute financially, no proposal has yet been made.”
DOC and LINZ indicated they could not contribute financially to the project, while TBHS would not commit to making a financial contribution to the bridge providing access to its John Scott Lodge.
